Vietnam's Department of Animal Health on Wednesday confirmed that over a thousand chickens in the capital city of Hanoi were killed due to the deadly bird flu, raising the number of affected localities in the region to four.

The DAH, under the Vietnamese Ministry of Agriculture and Rural Development said the deadly avian virus already resulted to the deaths of 1,150 out of 1,400 chickens in two farms in Dong Anh district.

The department said initial laboratory examinations on the fowls, indicate the chickens were positive of the H5N1 strain.

The local Veterinary Bureau has slaughtered all of fowl on the farms, and detoxified and disinfected the farm to prevent the disease's spread.

Bird flu outbreaks were first recorded in December 2003. Since then, dozens of millions of fowls all over the country, have been culled to prevent the spread of the disease.